7M-GE into 88 MX-73R e'ffin dramas

[Nerd Noob]

Hi all,
Long story short
I've got to fit this 7M-GE auto into a 87 MX-73 auto and get it going.
I've been working at this for a while now researching everything I can and the engine is in and running and so close but have some issues with shifting strange under power and idling fast up and down to near stall in P and N once warm. I've really struggled with correct wiring diagrams, pin outs and colours of wires with nearly every thread 404'd for good reason, or different to what I have. If you guys could help me with this I'll be happy to right up a good thread on what it takes to do. I'd also recommend doing a 2JZ non turbo if your P plated like this kid, for all the frigging work it's taken. Unless you got the shit free and you got plenty of time, patience and knowledge.
Thanks in advance and yeah I know, cool story bro!

[Defiance]

Why did you end up going back for a 7M again?

Should just do 2j to start with....

Its going to be the same dramas with the Wiring from the 7m anyway....

Are you sure its actually a good motor not like the 99% of the rest of them with a Blown H/G to start with?

[Nerd Noob]

It's not my car and the kid has no money. Like I said long story helping out a mates kid. The 87 MX-73 came with a 5M-GE which he toasted and he sourced this replacement engine (7M-GE) with a free car (89' MX-83) that has allowed me to use bits and pieces to make it fit. And the wiring is very different being the 5M has 2 computers and 7M only one. I've used the 7M engine harness and all associated engine hardware so there's no conflict with the ECU and it's mapping. It's all just a process of getting the body harness to mate with the engine harness. And the engine is fine as I tested it before fitting, although a bit old. I'm not new to mechanics, just new to all this electrical being an older guy.

Why did you end up going back for a 7M again?

Should just do 2j to start with....

Its going to be the same dramas with the Wiring from the 7m anyway....

Are you sure its actually a good motor not like the 99% of the rest of them with a Blown H/G to start with?

[Nerd Noob]

After doing some more research and testing, I've worked out the ISC valve is wide open and not closing and being regulated like it should via the ECU as there is no power going to it. Took it out and tested as per Toyota spec and all OK but no power going to B1 or B2 terminals. I fitted it while extended which closed the port and has brought the idle back down. Obviously the ECU is sensing the high idle and shutting the injectors down for a second or two to control the idle escalating beyond a the 2000 mark like it wanted to. Does anyone have an idea on this?

[Nerd Noob]

Did some dissecting of the old 5M harness and traced the power wires for the ISC back to the B+ wires which also power the injectors. On the wiring diagram http://home.exetel.com.au/madmont/mx83engine.jpg I've found that's closest to what I got for MX83, it shows power coming from EFI main relay with black/red wires which splice before going in to power the ISC 6 pin plug and feeding the 2 middle pins B1 and B2. So I found a stray bk/rd wire from the MX83 engine harness square grey plug (or B3), probe it and find that it is the power wire. I spliced into B+ for the ECU which I took off one of the heavy gauge blk/yel wires (which I'm guessing some others are bk/org) coming out of a yellow 2 pin round plug behind the MX73 battery which fed power to one of the 5M injector circuit (3 injectors per wire)
Here is the ISC testing proceedure if anyone needs it
http://wilbo666.pbworks.com/w/file/f...SA-1990%29.pdf page 281 of 1339

So I hook it up and test but no worky open and shut. I use the test method to open it, cause you cant pull it open only push close, and bolt it back into position extended which closes off the extra air and keeps the revs down but until it's cold again, I got no way of testing it to see if it will lift the revs (i.e open by itself.) Anybody with knowledge of how this is supposed to work? I gather that the ECU earths out the S pins in sequence to open and close but it seems to not want to even with power. I even through an earth lead on the ECU case to be sure

[Nerd Noob]

Took it for a test drive and it's running 7M strong but just dies when you get to about 5000 rpm on the dash tacho. I don't know if there's any difference to how the dash would work for the 5m v's 7M but I image that it's the same and I'm not hitting some type of rev limiter. The thing will do 140 in top without fuel starve so I'm discounting that idea. Any gear about 5000, buuuuurrrrrrrrrrrrrr. Left off and it's good again and it pulls well till then

[wilbo666]

Hi,

As a suggestion, I'd say the wiring of an engine conversion is something needs to be done with a great deal of attention to detail - if you want the finished product to function as it did in the original vehicle!...There is much danger in just finding a "stray bk/rd wire" and "which I'm guessing some others are bk/org".... :S (Toyota change wire colours a LOT, I try and avoid using wire colours alone...).


SO that said I don't believe that you have wired up the +B circuit as it should be. And as a result your ISCV isn't able to operate correctly.

You should have a relay called the "EFI Main Relay" that is controlled by the M-REL pin on the engine ECU. This is what supplies power to +B. The engine ECU leaves this on for a few moments after then engine is turned off, and when the engine has stopped running the engine ECU fully opens the ISCV for the next engine start. You haven't hooked up M-REL and as a result the ISCV looses power as soon as you turn the Ignition off, and the engine ECU can't open it...

Have a read of <this> page on my wiki

Also maybe you should check to see if you've wired up the engine ECU +BATT terminal to constant fused power from the battery. The 5M-E engine ECU doesn't require this, so there isn't a wire in the existing engine loom at the engine ECU area. i.e. you need to add it and the fuse in specifically.

Cheers
Wilbo

[petergoudie]

Are the diff ratios the same? If not the ecu might think the engine is revving higher than what it is.

Also, have you checked to see if the gearbox is in overdrive 4th or stuck in third?

[wilbo666]

Check the NSW switch wiring for the rev limit issue...
See <here>

Sorry, forgot to mention this in my first post...

Cheers
Wilbo

[Nerd Noob]

Thanks for the replies. Actually gained a few bits and pieces of knowledge from your Wiki so thanks a lot for having that available. The power wires I'm sourcing for the B+ were the power wires for the original injectors and such, which I believe came from the main EFI if I remember correctly. I'll check to see how long that stays powered for after shut down. The NSW from ECU was hard to get a definite for and as such have it spliced into the the starting wires(blk/white heavy gauge) that comes back from the NSW to starter as that's the way I could work it out from the wiring diagram posted earlier, so it's only seeing power while cranking in P or N. My gut feeling was this is wrong, but what's a noob to do? Got the O/D working now also but it hasn't fixed the rev limit. Not sure on dif ratios and but not sure how that may affect every gear at the same revs???
The blk/rd to the ISCV is the correct feed wire to the ISC which I determined through continuity tests, connecting power and probing for power while running, but yeah, it may not be getting powered by the correct source that remains powered for a short while after shut down. I'll do some more checks and get back to you. The car is getting picked up though today as the engine is in and running and driveable as per the work scope. Not just the way I'd like it to be fininished and working perfectly. So bloody close but

[Nerd Noob]

O/D working like it should.Click button goes up or down accordingly. Not sure on ratios

Are the diff ratios the same? If not the ecu might think the engine is revving higher than what it is.

Also, have you checked to see if the gearbox is in overdrive 4th or stuck in third?

[Nerd Noob]

Not exactly sure on how that goes all though it looks simply enough. It was a very big weekend for an old brain. I've got a wire spliced into the heavy gauge wire that comes back from the NSW (so only sees power while cranking in P or N) going straight to the NSW pin on the ECU

Check the NSW switch wiring for the rev limit issue...
See <here>

Sorry, forgot to mention this in my first post...

Cheers
Wilbo

[Nerd Noob]

Did some checks on my wiring. To run the B+, Batt and M rel into the cab from behind the battery where the old 5M harness plugged into these, I used a length of trailer plug cable to keep it neat and labelled the different coloured wires at the battery end. So we have 12v full time to Batt and B+ is tied into the power of main relay so the ISC is getting the delayed supply of power after shut down and I can actual hear it now openning up as the power turns off. On start up without foot application the idle will rise and return to a steady idle as it should so maybe that was all just a it sticky. The 4500-5000 cut out is still persistent though.

[Nerd Noob]

I've also given my log in to the owner (Jack), so he may chime in with updates and pics if he wants. Hi Jack when every you get around to reading this and hope it went well on way home. No abusive texts so I'm guessing so. I have a few pics I'll upload when I get the chance, and give a bit of a run down on what it took and what I had to modify/change/shoehorn to work.